1. Field of the Invention
The invention is directed to an improved fuel injection apparatus for an internal combustion engine, including a high-pressure fuel pump and a fuel injection valve connected to the fuel pump for each cylinder of the engine.
2. Description of the Prior Art
A fuel injection apparatus of the type with which this invention is concerned is known from DE 198 35 494 A1. This fuel injection apparatus has a high-pressure fuel pump and a fuel injection valve connected to it for each cylinder of the internal combustion engine. The high-pressure fuel pump has a pump piston that is driven into a stroke motion by the engine and delimits a pump working chamber connected to a pressure chamber of the fuel injection valve. The fuel injection valve has an injection valve element that controls at least one injection opening and, acted on by the pressure prevailing in the pressure chamber, can be moved in an opening direction counter to a closing force in order to open the at least one injection opening. An electrically actuated control valve at least indirectly controls a connection of the pump working chamber to a discharge region in order to control the fuel injection. When the pressure in the pump working chamber and therefore in the pressure chamber of the fuel injection valve reaches the opening pressure, then the injection valve element moves in the opening direction and opens the at least one injection opening. The injection cross section that is controlled by the injection valve element is always the same size. This does not permit an optimal fuel injection in all operating conditions of the internal combustion engine.